How should a scale be properly used in photographing a shoe impression and why is it used?
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What material is used to cast footwear impressions?
Dental stone
Name and briefly describe four methods of enhancing footwear impressions
specialized lighting and photographic techniques are nondestructive and therefore a good first method of enhancement. Impressions that are photographed can be digitally enhanced. Digital enhancement methods are often used to further enhance impressions th
What areas are examined in a footwear impression comparison?
Footwear wear examinations involve comparisons of both full and partial crime scene impressions with known shoes. The examination of the class characteristics of design, physical size, and general wear and the presence of any individual characteristics fo
What is the purpose of making known impressions of shoes during an examination?
during the examination made between a crime scene impression and suspects shoes, the examiner makes known impressions of the suspects footwear to assist in the evaluation and comparison of this evidence. It is used to assist the examiner in comparing the
Name three materials that can be used to lift a shoe impression that has been treated and enhanced with fingerprint powder on a nonporous tile floor, and indicate which one will make the most complete lift
- electrostatic lifting is a method that utilizes a high-voltage power source to create a static electrical charge that enable he transfer of a dry origin impression from the surface to a special black lifting film
- macrocell is a casting material that c
Some footwear impressions are latent or hardly invisible. Do these impressions contain suffice detail for examination?
yes because all impressions no matter what can potentially contain sufficient detail for meaningful examination result
What information can a shoe print provide in an investigation? Name at least three.
It can link scenes of crime
Location of impressions
Number of perpetrators
State if a partial footwear impressions can be examined and identified. Explain.
Some partial impressions represent only a small percentage of the shoe sole that created it but regardless all impressions can potentially contain sufficient detail for a meaningful examination result.
Are class characteristics or individual characteristics normally used to eliminate a shoe?
Yes because sometimes the difference in comparing shoes can be one small mark or groove
What four areas of the tread are involved in a forensic comparison?
- tread dimension or size
- tread design - tread blocks, grooves, and sipes
- wear features (when the tire wears down)
- random individual characteristics (cuts, tears, scratches, and abrasions that have occurred on the tire)
What is "track width"? Explain how it is measured
measurement from the center of one wheel to the center of the opposite wheel on the same axle
Differentiate between a "tire impression and a tire track
tire impression is when a tire contacts a surface, resulting in the transfer of the class characteristics of design and size
tire track is the relative dimensions between two or more tires of a vehicle
What does the term "OE" tires mean, and what are "replacement tires"?
-they are tires that are sold as equipment on new vehicles. OE tires of the same size and brand are used on thousands of the same make and model vehicle.
-Replacement tires are those purchased to replace worn or damaged tires, often the same design as the
What is the "DOT" number on a tire, and what are two important pieces of information that it contains?
it is a number that shows where and when the tire was made. The date and where it was made
What does the term "noise treatment" refer to?
when a tire turns under load, the tire tread blocks vibrate and produce harmonics or noise, and the tire industry has created tire designs that change the size (pitch) of the tread blocks around the tire, thus creating a variety of pitches. This and other
What are "tread wear indicators," and how often must they appear around a tire?
also known as a wear bar, is a raised rubber bar that is 2/32 inch above the base of the tire grooves. all tires over 12 inches in diameter contain a minimum of 6 markers
What is the Tread Design Guide, and how might it assist in an investigation with tire tread evidence?
it has photographs of most tires' designs. Investigators can use this to reference as and link a tread design from a crime scene to a particular design and a brand of tire
Should a cast be made of a three dimensional tire impression and if so why?
yes because it will provide an examiner with more information and will likely result in a far better examination result
Explain why it is important to document the positions of tire impressions at a crime scene, both photographically and otherwise.
Because if another vehicle drives over it on accident it could ruin the tread marks or if the weather ruins it as well, like rain or snow